This invention relates in general to cases for removably retaining environment-sensitive objects such as tape cartridges.
With the widespread increase in the use of magnetic tape for digital and analog recording and reproduction, many of these tapes are stored in cassettes, such as the so-called "Phillips-type" cassettes, and other cartridges of various configurations. Tapes stored in such cartridges are finding increased acceptance in many industrial and consumer markets where reel to reel tapes have previously been employed.
However, it has become widely recognized that the performance of these tapes is reduced considerably and their physical integrity impaired by contaminants such as dirt and dust. Even moreso, but less readily apparent, are the highly detrimental effects of humidity, elevated temperature, and magnetic and electromagnetic radiation. Immediate loss of recorded data may occur by subjecting the recorded tape to magnetic radiation. Exposure of tapes to humidity and elevated temperatures over a period of time may also have a detrimental effect on the performance and physical integrity of the tape. While these effects are not fully understood, it is known that exposure to elevated temperatures and/or humidity for a relatively short period of time (as when a tape is in a closed car in the sunlight) can cause marked degradation of the binders that physically hold the magnetic oxide to the tape. After such degradation, the oxide coating will start to flake off in the form of very small particles, which may occur after a period of several months. This effect can be extremely costly, particularly in digital recording techniques where packing density of 1,000 bits of data per linear inch are not uncommon. It is also known that not only is humidity itself detrimental to the tapes, but that reducing humidity also gives increased resistance to elevated temperatures (e.g., the oxide binders do not degrade as badly from elevated temperature when moisture level is reduced).
The present commercially available cases for environment-sensitive objects such as tape cartridges have various limitations and disadvantages including their failure to provide adequate and/or dependable protection from the deleterious effects of various elements of the external environment.
The present invention obviates these and other problems. In the form illustrated and described hereinafter there is a case comprised of two case sections which are each quadrilaterally shaped and hingedly connected together along one edge. An elongated torsion spring is used both to connect the two case sections together and to continuously bias them to the closed position. In the illustrated construction, the spring continues to bias the casing closed as the case sections are moved to an open position, and the casing will automatically shut when the sections are released. The need for a latch or the like is eliminted.
When the two case sections are in the closed position, an interior chamber is formed which is sized and shaped to retain the desired object. A pliable and resilient seal may be affixed to the peripheral edge of one of the case sections to maintain an air-tight seal around the entire case periphery when the two case sections are closed. In addition, a radiation shield may be provided, and a moisture absorbing material, such as a desiccant, may be located on the inner face of one of the case sections to dehumidify the chamber when the case is closed. The desiccant may be provided in a manner which both provides the desired moisture-absorbing capability and protection to the interior environment of the casing. Furthermore, a reflective exterior finish may be provided on the case to aid in reducing internal temperatures due to the sunlight or other radiated thermal energy.
The present invention also provides a unique method for assembling the two case sections, with the case sections being designed so that they can be very quickly and easily assembled by means of a torsion spring. In this connection, the spring may be simply bent and manipulated so as to interlock with the case sections.
It is, therefore, the primary object of the present invention to provide a case for removably retaining and protecting an environmentally sensitive object.
It is another object of the present invention to provide a case of the type stated where two case sections are held together and biased to a closed position by a simple torsion spring means.
It is another object to provide such case which provides an effective seal without the necessity for latch means or the like.
It is another object to provide a unique arrangement for removal of moisture from such a case.
It is a further object of the present invention to provide a case of the type stated which can be constructed in a wide variety of sizes and shapes in order to accommodate various forms of objects.
It is an additional object of the present invention to provide such a case which can be manufactured at a relatively low unit cost on a mass-production basis.
It is another salient object of the present invention to provide a method of assembling such a case where two case sections can be assembled quickly and easily with a minimum amount of manual labor.
It is a further object to provide such a method of assembly whereby the case sections are mechanically interconnected by the simple manipulation and interengagement with the case sections of a preformed wire torsion spring.
With the above and other objects in view, my invention resides in the novel features of form, construction, arrangement, and combination of parts presently described and pointed out in the claims.